Magnetic field adjuster for television picture tubes



Sept. 30, 1958 M. BAERMANN 2,854,598

MAGNETIC FIELD ADJUSTER FOR TELEVISION PICTURETUBES Filed Nov. 21, 1955INVENTOR. MAX BA ER MANN DWQQQ ATTORNEY United. States Patent MAGNETICFIELD ADJUSTER FOR TELEVISION PICTURE TUBES J This invention pertains tothe art of magnets and more particularly to a magnetic arrangement forproviding an adjustable strength and polarized magnetic field.

he invention is particularly applicable to providing an adjustablemagnetic field for the electron stream impinging upon the viewing screenof a television picture tube and will be described with particularreference thereto although it willbeappreciated that the invention hasbroader applications.

In the art of television picture tubes, it has heretofore been known toprovide around the periphery of the viewing screen a ranged that themagnetic strength and the magnetic polarity of each device may beindependently adjusted.

. One such device consisted of a round cup of non-permanentmagnetically-permeable material and magnet magnetized transversely toaxis of cup mounted for adjustment into and out of the cup as well asrotatable about anaxis through the cup. When the magnet is in the cup,its magnetic flux flows through the material thereof and the device hasa zero or substantially zero external magnetic field. As the magnet ismoved out of the cup, however, less and less of the flux passestherethrough and the external magnetic field of the device iscorrespondingly increased. The magnet can then be rotated about the axisto vary the orientation of its magnetic polarization relative to thepicture tube but without varying the strength of the previously adjustedmagnetic field.

One of theprincipal problems with such a device is the axial dimensionsrequired in order to obtain a full range of adjustment of the externalmagnetic field of the device. This is particularly so if the fullmagnetic force of the magnet is to be realized because in such a case asubstantial axial spacing between the cup and the magnet must beprovided. As this axial dimension actually is aradialdimension added onto the diameter of the television tube, it will be appreciated that acabinet much larger than the diameter ofthe tube itself must beprovidedin order to allow room from the magnetic devices.

The present invention contemplates and has for its principal object amagnetic device of the general type referred to which provides for readyadjustability of the strengthand polarity of the magnetic field, whichovercomes all the above referred-to difficulties, is simple inconstruction and cheap to manufacture.

Another object of the invention is the provision of a new and improvedmagnetic device for adjusting a magnetic field about the viewing screenof a television picture tube whichhas a minimum dimension on a radialline from the central axis of the tube.

A still further object of the invention is the provision of a new andimproved magnetic device which can have its magnetic field readilyadjusted from substantially zero, to ,the full total strength of themagnets employed.

,A.still further object is the provision of a device of the. typedescribed wherein all of the magnetically permeable material employedmay be used to create an external magnetic field.

.A still further object of the invention is the provision of a new andimproved device of the general type de scribed comprised of a pair ofmagnets in close-spaced plurality of magnetic devices so arfi Ficerelationship andso polarized and so adjustable relative to each otherthat the external magnetic field about the two magnets can be variedfrom substantially zero to a maximum consisting of the combined magneticstrength of the two magnets.

In accordance with-the present invention a plurality of permanentmagnets are mounted in superimposed close-spaced relationship with theplane of the magnetization-being generally parallel to each other, suchmagnets being adjustable about an axis transverse to the plane ofpolarization both relative to each other whereby the strength of theexternal magnetic field may be readily varied and as a group whereby thepolarization of the combined external magnetic fields may be readilyvaried.

Still further in accordance with the invention, a pair of disk-like edgepolarized magnetic members are provided in superimposed spaced opposedrelationship with each other, such members being adjustable eithersimultaneously or individually in the plane of the disk.

The mounting for the members may be as desired but in accordance withone phase of the invention the magnets are so mounted that either may beadjusted without disturbing the adjustment of the other.

Further in accordance with the invention, the magnet members may beprovided with external indicia to indicate the position of theindividual magnetic poles.

Still further in accordance with the invention there is provided for usein combination with the television picture tube having a viewing screena plurality of magnetic devices positioned around the edge of suchscreen, each device being comprised of a pair of superimposedrelastively close spaced magnets, eachmagnetized 'in a perpendicular to aradial line through the center plane of the tube, and eachbeingindependently adjustable about such radial line to adjust theexternal magnetic field thereof or adjustable as a unit to adjust themagnetic orientation of the adjusted magnetic field.

The magnets may be of any desired or usual shape including bar magnetsbut are preferably edge-magnetized disks. Also they may be of any knownmagnetic material but preferably one having a high magnetic stability.Further, the magnetic members may be of any relative size or relativemagnetic strength, it being appreciated that as one member is larger orstronger, the other may not be able to completely neutralize itsexternal magnetic field.

-The invention may take physical form in certain parts and arrangementsof parts a preferred embodiment of which will be describedin detail inthis specification and illustrated in the accompanying drawing which isa part hereof and wherein:

Figure l is a fragmentary side elevational view of the viewing end of atelevision picture tube in combination with magnetic devices allconstructed in accordance with the present invention and illustrating apreferred embodiment thereof. 1

Figure 2 is a front elevational view of Figure 1.

Figure 3 is an enlarged side elevational view of a mag netic deviceconstructed in accordance with the present invention.

Figure 4 is a top elevational view, with portions broken away, of Figure3; and

Figure 5 is a view similar to Figure 3 but showing a slightly modifiedembodiment of the invention.

Referring now to the drawing wherein the showings for the purposes ofillustrating the invention only and not for the purposes of limitingsame, the figures show a television tube A comprised of an outer shell10 and a viewing screen 11 having a central axis-12 with a plurality ofmagnetic devices 13 constructed in accordance with the present inventionarranged around the peripheryofw the tube A adjacent to viewing screen11.

In the embodiment of the invention shown, the magnetic devices B aremounted on a strap or band 14 of non-magnetic material which completelysurrounds the periphery of the tube. The outer shell of the tube A isformed preferably of a non-magnetic material.

Obviously, any other desired arrangement may be providedfor mounting themagnetic devicesB than the one shown. For example, the devices B may bemounted in the housing in which the tube A is mounted or the devices maybe mounted directly on the tube A by means of an adhesive ortheequivalent.

In the embodiment shown, each magnetic device B is comprised of a baseof non-magnetic material having a pair of openings 21 through whichfastening means 22 may extend for. fastening the. device to the strap14, and a pair of permanent magnetic members 24, 25 held in superimposedspaced opposed relationship by a compression spring are mounted on thebase 20 by a sleeve 26 extending through an opening in the base 20 andthe magnets 24, 25. The ends of. the. sleeve are reduced in diameter toreceive washers 30, 31 and are then flared over as at 28, 29 to maintainthe assembled relationship.

The spring 33 is in the form of a washer having outwardly extending arms34, 35 biased downwardly and upwardly respectively and is preferablykeyed to the sleeve 26 by means of a tab 37 extending into acorresponding groove in the surface of the sleeve 26.

The magnets 24, 25 may be of any known permanent magnetic material suchas the various Alnico alloys, the various known ceramic magneticmaterials and may be molded to the shape shown and bonded into suchshape either by a sintering process, use of a plastic binder or thelike. Themagnetism may be induced therein during 2 the molding processor after as is conventional.

In the preferred embodiment, the magnetic numbers 24, 25 are each of thesame diameter and are in the form of a flat circular disk with themagnetic pole being in the plane of the disk. Thus, as shown in Figure4,

both disks 24, 25 have a north polarity over approximately 180 degreesof their circumference and a south polarity over the opposite likeamount of the circumference. The pole strength tapers ofi gradually to apoint 40 of neutral polarity as is indicated by the height of theletters indicating polarity. The edges of the disks 24, 25 may havesuitable indicia 38, 39 respectively to indicate the center of andpolarity of each pole. Thus, the indicia 33 may be one color or textureto indicate a north pole and the indicia39 a difierent color ordifferent texture to indicate a south pole.

It will be noted from Figure 3 that the indicia 38, 39 are oriented onefrom the other. Each disk 24, 25 is rotatable in its plane about theaxis of the sleeve 26 and by so rotating the disks, the orientation ofthe pole of each may be adjusted either relative to each other or to thetelevision tube A.

Obviously, when the north poles are adjacent each other, the magneticstrength of the two disks will add to each other. If oriented 180degrees from each other so that a north pole is adjacent to a southpole, the external magnetic field of the two disks will be substantiallycancelled. The external magnetic field may obviously be adjusted by anyintermediate relative orientation of the magnetic poles.

With magnetic poles oriented as above indicated, both disks aresimultaneously adjusted to provide the desired magnetic polarity for thetelevsion tube A.

It will be noted that the arrangement for mounting the disks 24, 25 onthe base 20 assists in the making of such adjustments. The sleeve 26 isrigidly held to the base 20 and the spring is keyed to this sleeve.Movement of one magnet does not efiect the position of the other.

Figures 3 and 4 show the disks 24, 25 to be of the same diameter andshape and axial thickness. Obviously, the disks 24, 25 need not beidentically dimensioned as is shown generally in Figure 5 wherein theupper or outer disk 25' is of a somewhat lesser diameter than that ofthe lower disk 24. Normally, the disk 25' will then have a lesser totalmagnetic force than that of the disk 24 and even when a north and southpole are adjacent each other, the external magnetic field of the lowerdisk 24 will not be entirely neutralized. The relative axial thicknessand spacing of the two disks may be varied as desired to be eithergreater or less than that shown.

Furthermore, the members 24, 25 have been shown as being circular inelevational view. Obviously, the members could have any other extrenalshapes such as rectangular, square, octagonal or the like. Also the disk25 could be cup-shaped so as to fit over the outer edge of the disk 24or vice versa. Adjustment of the disks is more clifiicult but a morecomplete neutralization or a stronger overall external field can beobtained.

The invention has been described with reference to a preferredembodiment. Obviously, the invention may take physical form in otherarrangements differing radi-- cally from the embodiment hereindescribed. It is my intention to include all such embodiments insofar asthey come within the scope of the appended claims. Having thus describedmy invention, I-claimz 1. In combination with a television picture tubehaving a viewing screen a plurality of magnetic devices positionedaround said tube adjacent to said screen, each device being comprised ofa plurality of magnets in super imposed close spaced relationship andmagnetized in a plane perpendicular to a radial line through the centerof said viewing screen, each magnet being independently adjustable aboutsuch radial line.

2. In combination with a television picture tube having a viewing screena plurality of magnet devices positioned around the edge of said tubeadjacent to said screen, each device being comprised of a pair ofsuperimposed close-spaced permanent magnets each magnetized in a planeperpendicular to a radial line through said screen, each beingindependently rotatable about such radial line.

3. In a magnetic device for providing an adjustable strength andpolarized magnetic field about a television viewing screen. a pair ofmagnets in superimposed relatively close-spaced relationship and eachadjustable relative to the other about an axis, each member beingmagnetically polarized in a plane perpendicular to said axis.

4. A magnetic device comprised of a pair of bi-polar magnets insuperimposed close-spaced relationship, means mounting said magnets foreither relative adjustment in the plane of the poles or for simultaneousadjustment of the plane of said poles.

5. A magnetic device for providing an adjustable strength and polarizedexternal magnetic field comprising in combination a base, a firstmagnet, a second magnet having a parallel plane of polarization to saidfirst magnet, means mounting said magnets in superimposed spacedrelationship on said base, friction means permitting said magnets to befixedly adjusted relative to each other and to said base.

6. The combination of claim 4 wherein said magnets are in the shape offlat disks and are edge magnetized.

7. The combination of claim 1 wherein indicia are provided on thesurfaces of said magnets to indicate the magnetic polarity thereof.

References Cited in the file of this patent UNITED STATES PATENTS2,258,643 De Gier et al. Oct. 14, 1941 2,513,221. Webb June 27, 19502,513,929 Gethmann July 4, 1950 2,541,446 Trott Feb. 13, 1951 2,591,159Kabuss Apr. 1, 1952 2,646,522 Shaw et al. July 21, 1953 2,717,323 ClaySept. 6, 1955 v

